• Our booking engine at tickets.railforums.co.uk (powered by TrainSplit) helps support the running of the forum with every ticket purchase! Find out more and ask any questions/give us feedback in this thread!

Japanese HSR Pantograph Fence/Shroud

Status
Not open for further replies.

Speed43125

Member
Joined
20 Jul 2019
Messages
1,131
Location
Dunblane
Hello,
I was wondering why Japanese high speed trains tend to have shrouds/fencing next to the pantograph, whereas contemporaries in Europe do not. Wind? Interfering with active tilt?

Any insight would be greatly appreciated.
Sorry if that isn't the technical term, I had trouble finding much at all online.
 
Sponsor Post - registered members do not see these adverts; click here to register, or click here to log in
R

RailUK Forums

WideRanger

Member
Joined
15 Jun 2016
Messages
325
I'm not sure we're talking about the same thing, but there are often things that look like wings either side of the pantograph. I understand that these are to reduce the noise from the train to its environment.
 

swt_passenger

Veteran Member
Joined
7 Apr 2010
Messages
31,266
It won’t be about tilt, as the pantographs on tilting trains remain central (with respect to the track position) and the train tilts under them.
 

edwin_m

Veteran Member
Joined
21 Apr 2013
Messages
24,793
Location
Nottingham
It won’t be about tilt, as the pantographs on tilting trains remain central (with respect to the track position) and the train tilts under them.
I think the OP is referring to a sort of fairing around the pantograph well, which partly hides the pantograph itself from view. These are I believe to reduce noise. European trains don't have them, probably because they would be out of gauge if the train had to be dragged on a non-electrified line.

The pantograph on a tilting train does indeed remain central relative to the track, but that means it moves to one side relative to the train roof. So it could clash with such a fairing. But that can't be the reason European trains don't have them, as non-tilting trains don't either.
 

JonasB

Member
Joined
27 Dec 2016
Messages
921
Location
Sweden
European trains don't have them, probably because they would be out of gauge if the train had to be dragged on a non-electrified line.

I realise that would be a problem in the UK, but I don't think it would be a big issue in the rest of Europe where the loading gauge is larger and non-electrified lines are rarer.

The reason for them seems to be noise reduction: https://link.springer.com/article/10.1007/s10409-013-0028-z Why they do not exist on European high speed trains is a good question. But my guess is that Japan is more densely populated and there are more people living close to high speed lines.
 
Last edited:

edwin_m

Veteran Member
Joined
21 Apr 2013
Messages
24,793
Location
Nottingham
Also I think even in Continental Europe the wire height varies (except on high speed lines) and these items would impose a minimum.
 

The Lad

Member
Joined
22 Jan 2015
Messages
408
It'll reduce the chance of touching the pantograph horns with your brolly
 

Three-Nine

Member
Joined
5 Aug 2015
Messages
110
If they're a noise reducing measure, the answer might be the same as to why shinkansen tend to have such impressive nosecones - its to reduce noise upon entering/exiting the many tunnels they have to travel through, though my understanding is thats usually due to air being pushed through in front of the train so I don't think that would apply to a pantograph.

Shinkansen do also pass through many built-up areas, at least on the Tokkaido mainline, so noise reduction is probably more of an issue for the Japanese.
 

WideRanger

Member
Joined
15 Jun 2016
Messages
325
If they're a noise reducing measure, the answer might be the same as to why shinkansen tend to have such impressive nosecones - its to reduce noise upon entering/exiting the many tunnels they have to travel through, though my understanding is thats usually due to air being pushed through in front of the train so I don't think that would apply to a pantograph.

Shinkansen do also pass through many built-up areas, at least on the Tokkaido mainline, so noise reduction is probably more of an issue for the Japanese.
It's also the primary reason why the newest Shinkansen trains have a flexible material between the carriages, to reduce noise caused by the wind in the gaps. It helps streamlining and therefore efficiency too.
You will also note that most Shinkansen tracks that are at full line speed but not in tunnel and high walls. These are the same as use in Japanese motorways - to reduce noise impacts in the residential areas that can often be found very close to the tracks.
 

edwin_m

Veteran Member
Joined
21 Apr 2013
Messages
24,793
Location
Nottingham
If they're a noise reducing measure, the answer might be the same as to why shinkansen tend to have such impressive nosecones - its to reduce noise upon entering/exiting the many tunnels they have to travel through, though my understanding is thats usually due to air being pushed through in front of the train so I don't think that would apply to a pantograph.

Shinkansen do also pass through many built-up areas, at least on the Tokkaido mainline, so noise reduction is probably more of an issue for the Japanese.
I believe the reason for the long noses is the pressure pulse that can build up in front of the train in tunnels and when it gets released at the portal it creates something like a sonic boom. This wasn't really known about when the first Shinkansen were built so they had to compensate by building later and faster trains with long noses, presumably to help the air escape round the side instead of piling up in front. European HSRs learned from that experience and have tunnel portals with a more gradual opening and/or ventilation holes, so the pressure wave can dissipate.
 

Speed43125

Member
Joined
20 Jul 2019
Messages
1,131
Location
Dunblane
I believe the reason for the long noses is the pressure pulse that can build up in front of the train in tunnels and when it gets released at the portal it creates something like a sonic boom. This wasn't really known about when the first Shinkansen were built so they had to compensate by building later and faster trains with long noses, presumably to help the air escape round the side instead of piling up in front. European HSRs learned from that experience and have tunnel portals with a more gradual opening and/or ventilation holes, so the pressure wave can dissipate.
Ah, that's interesting. That would figure, thanks for the insight.
 

Yossarian22

Member
Joined
27 Aug 2019
Messages
14
Location
United Kingdom
So really late reply but Japan has incredibly strict noise laws. Thus the whole pantograph design is based around noise reduction. Not only are those farings for noise reduction but the pantograph itself is very carefully designed. If you look at Shinkansen pantographs they actually have little holes in them to allow air through. This reduces vortexes behind the pantograph and reduces noise. Furthermore, anything that can be hidden is. If you look at modern European pantographs they have a massive hinged double arm and a lot of exposed equipment on the roof. On the shinkansen everything possible is hidden.
On some shinkansen, the fairings are being removed from the design as they create noise themselves. They would reduce noise for older bulky pantographs but as Japan Rail design skinnier and skinnier pantographs the fairings do more harm than good.

What is interesting is that designs differ from train to train with designers always experimenting on what could be the perfect pantograph. It is a very much obsessive F1 mentality to train design
 
Last edited:

jopsuk

Veteran Member
Joined
13 May 2008
Messages
12,771
as well as the strict noise laws (which I guess are needed as the Shinkansen lines run through very heavily populated places at full speed) a lot of the aerodynamic requirements with the design of the stock is predicated on the tunnels on the older lines only really having been built for 160mph trains. Running faster trains without creating excessive noise at the tunnel mouths has led to the weird noses.
 
Status
Not open for further replies.

Top